Association of the Q121 variant of ENPP1 gene with decreased kidney function among patients with type 2 diabetes.
BACKGROUND
Insulin resistance has a role in diabetic kidney complications. The K121Q (lysine to glutamine substitution at amino acid 121, encoded by single-nucleotide polymorphism rs1044498) variant of the ectonucleotide pyrophosphatase/phosphodiesterase gene (ENPP1) has been associated with insulin resistance and related vascular complications in patients with type 2 diabetes (T2D) in many, although not all, studies. This study investigated whether the ENPP1 Q121 variant modulates the risk of decreased glomerular filtration rate (GFR) in patients with T2D.


METHODS
Cross-sectional study.


METHODS
2 diabetes units from Italy (in Gargano and Padua) and 1 from the United States (Boston, MA) recruited a total of 1,392 patients with T2D.


METHODS
The ENPP1 Q121 variant.


METHODS
Estimated GFR from serum creatinine, urinary albumin excretion, blood pressure, hemoglobin A(1c), triglycerides, total cholesterol, and high-density lipoprotein cholesterol.


RESULTS
Decreased GFRs (ie, estimated GFR <60 mL/min/1.73 m(2)).


RESULTS
In the Gargano and Boston populations, according to the dominant model of inheritance, Q121 carriers (ie, individual with either KQ or QQ alleles) had an increased risk of decreased GFR: odds ratios (ORs) of 1.69 (95% confidence interval [CI], 1.1 to 2.6) and 1.50 (95% CI, 1.0 to 2.2), respectively. In the Padua set, the association was in the same direction, but did not reach formal statistical significance (OR, 1.77; 95% CI, 0.7 to 4.5). When the 3 studies were pooled, Q121 carriers showed an increased risk of decreased GFR (OR, 1.58; 95% CI, 1.2 to 2.1; P = 0.002). Also, pooled mean differences in absolute GFRs were different across genotype groups, with Q121 carriers showing lower GFRs compared with KK individuals (P = 0.04).


CONCLUSIONS
P values not approaching a genome-wide level of significance.


CONCLUSIONS
Our data suggest that patients with T2D carrying the ENPP1 Q121 variant are at increased risk of decreased GFR.
De Cosmo
Salvatore
S
Unit of Endocrinology, Scientific Institute Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy. sdecosm@tin.it
Minenna
Antonio
A
Zhang
Yuan-Yuan
YY
Thompson
Ryan
R
Thompson
Robert
R
Miscio
Giuseppe
G
Vedovato
Monica
M
Rauseo
Anna
A
Saller
Alois
A
Mastroianno
Sandra
S
Pellegrini
Fabio
F
Trevisan
Roberto
R
Fioretto
Paola
P
Doria
Alessandro
A
Trischitta
Vincenzo
V
D000419:Albuminuria; D019943:Amino Acid Substitution; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics* / Q000503:physiopathology; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D010727:Phosphoric Diester Hydrolases / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D011755:Pyrophosphatases / Q000235:genetics*
D010727:Phosphoric Diester Hydrolases; C065962:ectonucleotide pyrophosphatase phosphodiesterase 1; D011755:Pyrophosphatases